1. Field of the Invention
The present invention relates to a flaskless casting line, and more particularly to a flaskless casting line in which a casting take-out operation can be carried out favorably.
2. Description of the Prior Art
In a conventional flaskless casting line, a sand mold molding machine, a molten metal pouring machine, a casting take-out machine and a sand recovery machine are disposed along a conveyor apparatus for transferring sand molds which is operated at intervals. The operation environment cannot be said favorable in view of heat and dust. Hence, it has been desired recently to automate the operation of the conventional flaskless casting line.
As for the casting take-out machine for taking out a casting from a sand mold, it has been known that the various types of the machines are available. For instance, a casting take-out machine which has a drum cooler disposed at an end of a conveyor apparatus has been employed widely in the current casting industry. When sand molds are put into the rotating drum cooler, the sand molds are divided into sand and castings.
Further, a casting take-out machine having a vibrator sieve disposed at an end of a conveyor apparatus has been put into a practical use. In the machine, sand molds are dropped into the vibrator sieve to divide the sand molds into sand and castings.
Moreover, a casting take-out machine is disclosed in Japanese Unexamined Utility Model Publication (KOKAI) Nos. 6146/1988, 163260/1988 and 170066/1988 and Japanese Unexamined Patent Publication (KOKAI) No. 252666/1988. The casting take-out machine is disposed in a manner facing an end of a conveyor apparatus, and has a placement arm to be pierced into a lower portion of a sand mold disposed below a casting and a pressing arm to be pierce into an upper portion of the sand mold disposed above the casting. When taking out the casting form the sand mold, the arms are first pierced into the sand mold, and thereafter they are moved relatively in a direction approaching each other to hold the casting in the vertical direction. Then, the arms are rotated or moved straight in a horizontal plate to take out the casting from the sand mold.
However, in the casting take-out machine having the drum cooler or the vibrator sieve, the castings are taken out in a various attitudes and positions. Accordingly, it has been impossible to automate the handling operation after the casting operation, for instance, an operation for placing the castings onto a casting transferring conveyor apparatus. Hence, the operation should be carried out manually and consequently heavy labors have been imposed on the operators in an inferior environment.
The casting take-out apparatus disclosed in the above-mentioned publications is intended to take out the casting in a predetermined attitude, thereby solving the problems of the casting take-out apparatus having the drum cooler or the vibrator sieve. However, the casting take-out apparatus disclosed in the publications suffers from the following problems:
The first problem is that the stop positions of the sand molds fluctuate as an conveyer apparatus is operated at intervals. Namely, the individual sand molds constituting a flaskless sand mold row are compressed in a transferring direction by an impact force resulting from the activation and deactivation of the conveyor apparatus during the transfer operation. Strictly speaking, the movement distance of the conveyor apparatus is not constant for each of the transfer operation. As a result of these problems, the stop positions of the sand molds fluctuate when the sand molds arrives under the casting take-out apparatus. In the case that the stop positions of the sand molds fluctuate under the casting take-out apparatus, the relative position of the take-out arm and the casting varies in the transferring direction even when the take-out arm is pierced into the sand mold by a predetermined depth, and accordingly the following handling operation is troubled. For instance, in the case that the take-out casting should be placed onto a casting transferring conveyor, it is hard to carry out the placement of the casting when the casting is not held at a predetermined position of the take-out arm, i.e., at a front end thereof in general. Further, there is a possibility that the casting is hooked incompletely onto the take-out arm. If such is the case, the casting take-out operation also results in a failure.
The second problem is that the gap, the slippage and the breakage and the like occur in the boundaries between the individual sand molds constituting the flaskless sand mold row as illustrated in FIG. 5. Consequently, the castings get out of position, thereby causing a failure casting take-out operation and damaging the castings with the take-out arm.
The third problem is that the casting take-out apparatus is arranged so that it holds the casting, especially the product portion thereof, by a large holding force in the vertical direction. Hence, there is a possibility that the take-out arm damages the casting. In the case that the casting surface to be held is not flat in the horizontal direction or that the casting surface to be held has an insufficient area, the possibility becomes more likely to happen. Further, in the case that various kinds of castings should be molded in different sand molds on an identical flaskless casting line, it is extremely hard to hold the castings having a configuration varying each other with the casting take-out apparatus.